Hello everyone!

I have a 2014 Vrs TSI 2.0 petrol. I recently had to have the water pump / thermostat assembly replaced, but I have yet another coolant leak. Long story short, I was sure it was the bottom radiator hose, so after a fight and grazed knuckles replacing it...of course, it's not that.

 

It's coming from whatever the hose clips onto. It looks like some kind of unit bolted to the front of the engine, underneath the inlet manifold. I've tried looking online, just can't find out what it is! Or if it can be repaired, how to remove it etc.

 

As always, I'd be ever so grateful for some help please! Along with having to have the sump replaced for an oil leak last month too, I'm gonna christen this car 'the sieve...'

 

Really having a sense of humour failure with it now. Thanks again everyone x

That coolant leak sounds like being from the Charge Cooler unit.

5 hours ago, Warrior193 said:

That coolant leak sounds like being from the Charge Cooler unit.

Heya. I've had a look at these on the Internet, not sure it is this? Amy other ideas?

Oil cooler?

 

That may be fed direct from the block cooling jacket though.

 

Maybe the Tsi does not have one? I'm more used to diesels and that is the position of the oil cooler on them.

Not sure...can't really see it but what I can see looks like a black plastic something, with a round metal cover on the very bottom about 15mm across, which looks like it's held on by 3 bolts. It has at least two outlets on the front at the bottom, one of which is where the offside radiator hose (the one with the temp. sensor in it) connects to.

 

If anyone has a photo of the front of this engine, I could point to it? Cheers!

Edited 31 January, 20251 yr by Ray Luxury-Yacht

Can you post your engine code ID letters? This is the 3 or 4 letter code in front of the engine number and can be found on your V5 document. I assume your engine is EA888 G3, is that correct? 

14 minutes ago, Warrior193 said:

Can you post your engine code ID letters? This is the 3 or 4 letter code in front of the engine number and can be found on your V5 document. I assume your engine is EA888 G3, is that correct? 

Heya. It's EA888 yes, no idea what gen, the car is 2014. The engine number is: CHHB******

 

Cheers!

Ok been looking over the Internet, for some reason really struggling to find out what this thing is. The only picture I've found so far is this one. It looks like it's the green thing in the middle of the pictuee. The pipe that the radiator hose connects onto is at the bottom, it's escaped the green tint and it's grey but you can see it.

 

So, anyone got any ideas what this green thing is? It's the thing that seems to be leaking coolant.

Cheers!

Yes, the green item and the source of all the main coolant pipes is the thermostat housing.

 

On the quick release connectors with retaining flips, the orings are replaceable. 

 

From my recollection, almost all the connections at the thermostat end are spring clips.

 

 

If it was done at a garage I'd take it in under warranty.

 

I love doing jobs twice, but despite being pretty thorough it happens to me too. Currently thinking I may need to go bac in to remove the ancilliary bracket and oil cooler despite having replaced the two gaskets and oil cooler and torqued it to spec...

 

It's a bit of a bugger to get to aswell... cooling fans out, main coolant pipes unplugged, charge air pipe out, alternator out, air con comp tied up out of way.... 

 

Maybe my ancilliary bracket sealing face is no longer perfectly square... as I say I love doing jobs twice!! 

Edited 2 February, 20251 yr by TheClient

7 hours ago, TheClient said:

Yes, the green item and the source of all the main coolant pipes is the thermostat housing.

 

On the quick release connectors with retaining flips, the orings are replaceable. 

 

From my recollection, almost all the connections at the thermostat end are spring clips.

 

 

If it was done at a garage I'd take it in under warranty.

 

I love doing jobs twice, but despite being pretty thorough it happens to me too. Currently thinking I may need to go bac in to remove the ancilliary bracket and oil cooler despite having replaced the two gaskets and oil cooler and torqued it to spec...

 

It's a bit of a bugger to get to aswell... cooling fans out, main coolant pipes unplugged, charge air pipe out, alternator out, air con comp tied up out of way.... 

 

Maybe my ancilliary bracket sealing face is no longer perfectly square... as I say I love doing jobs twice!! 

Ah, so THIS is the famous thermostat housing??? See, for some reason best known to myself, I thought that was bolted to the offside of the engine. I think because it's belt driven I assumed it was located, well you know, where the other belts are...

 

So where is the belt for this driven from?!

 

Well anyway, this waa replaced at a main dealer 18 months ago at the last service. Reckon they'll replace it for free this time? I mean failure after 18 months isn't reasonable really, is it?

 

Thank you so much for your help, really appreciate it 😊 

Thermostats are passive devices, not belt driven.

1 hour ago, J.R. said:

Thermostats are passive devices, not belt driven.

Water pump on the end...

 

Yeah the water pump bolts onto the end of the thermostat housing and is driven off a pulley off the end of the balance shaft if I'm remembering correctly.

 

Definitely not driven off the aux belt on the other side. It kinda sits dead under the middle of intake manifold. But water pump bolts up to the nearside end.  Anyway....

 

There's a 2 year warranty isn't there so they should. It may just be a coolant hose or spring clip this time but it all would of been removed and refitted. 

 

The thermostat is an electromechsnical device with servo actuation and electronic control. A TMCU thermal control management  unit. No longer a bimetallic valve employed in this engine. 

More complication of proven reliable simple technology.

 

Vehicle thermostats aside from someone deciding to over-complicate things like above were always expanding wax filled capsules not bi-metallic, very simple, very reliable, easy to diagnose when they did play up.

More complicated, yes - but there are obvious benefits in quicker engine warmup - reduced wear and emissions and increased economy.

No question about it, I appreciate the accelerated warm up of my EU5 diesel, much much faster than the preceeding EU4 and EU3 Tdi's that I had and it manages to do so with a standard wax capsule thermostat.

 

I do have the sliding sleeve bellows on the water pump to one day bite me on the bum but for the moment I am profiting from it functioning, even that is powered by the coolant flow albeit via a solenoid valve.

 

I'm not convinced about the reduced wear and economy, the heater gives heat far sooner but each joule of energy I gain there is one joule less to warm up the engine oil, once the diesel cycle is self sustaining (post pre-heat) there is no additional enrichment contrary to a petrol engine. Some de minimus friction losses but having watched my fuel economy like a hawk for 20 years I dont notice any measurable decrease after a winter cold start compared to a summer one, there is only a 7% difference in absolute temperature.